High performance of active carbon-based supercapacitor introduced with NiSO₄ and CoSO₄ redox active electrolytes in acid media

Abstract

The effects of incorporating NiSO4 and CoSO4 as redox additives into an H2SO4 acid medium to improve the functionality of a capacitor that is based on active carbon were studied using impedance spectroscopy, galvanostatic charge-discharge, and cyclic voltammetry. The power density (432 W kg−1 and 426 W kg−1), energy density (55.2 Wh kg−1 and 49.8 Wh kg−1), and specific capacitance (924 F g−1 and 842 F g−1) were achieved in electrolytes of NiSO4–H2SO4 and CoSO4–H2SO4, respectively, assuming a density of 1 A g−1, through diffusion-controlled redox reactions at the negative electrode.